Wireless transmitting apparatus



Feb. 2 1926; 1,571,373

N. E. DAVIS WIRELESS TRANSMITTI NG APPARATUS Filed Dec. 5, 1921 70 1 0/14? gave/0hr Suva rate: NORMAN E. DAVIS 351 his Gum/m1, )2 HQ &

Patented idcb. Z, 1926.

UNETELE 1 tennis earner FFICE.

NORMAN EUSTAGE DAVIS, OF CHENE BOUBG, NEAR GENEVA, SWITZERLAND, AS- STGN'OR T0 RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE.

WIRELESS TRANSMITTING AIPPARATUS.

Application filed December 1 0 aZZ whom 2'23 may concern: 7

Be it known that I, NORMAN EUsTA oE DAVIS, a subject of Great Britain residing at Hotel des 4r. Nations, Chene Bourg, Switzerland near Geneva, have invented certain new and useful Improveme'ntsun Wireless 'llransmitting Apparatus, of which the following is a specification accompanied by drawings.

According to a method or transmitting wireless signals which is now frequently used a coil which is coupled to the aerial circuit is shortc' *cuited by the sending key. ilhile this arrangement has certain advantages, it has also certain disadvantages, especially for rapid workmg; some of these are due to the fact that while the actual signal is made when the key opens and the coupling coil is thus unshorted, the signal is only cut off when the key contaht has travelled across the gap between it and its fixed contact.

According to this invention signalling 1 s effected by shorting and unshorting a coil coupled to the aerial circuit but the signal is made when the key closes. This is offected by employing two independent eoupling coils so arranged that with both 1n circuit they are in opposition and the current in the aerial is therefore practically nil. A ending key is so arranged that when it is closed one of these coils is short-circuited, while the other coil becomes efiective.

The invention is illustrated by the accompanying diagram, in which A is an aerial having coupled to it two coils B and C so arranged that with both in circuitv they are in opposition and the current in the aerial is therefore practically 1111. These two coils form part of an oscillatory circuit D in which oscillations can be set up, sav, by a valve generator. The coil C can be shortc-ircuited by a signalling key E. When the key contacts are closed, the coil C is shortcircuited and the full energy is passed to the aerial by coil B.

In order to avoid sparking at the key contacts it is desirable that the coil C should have a small self inductance and that the leads to and from the key should be as short as possible and of small impedance.

As it can be arranged that there is prac 3, 1921. Serial No. 519,797.

tically no change in operation ofthe transmitting set with the key opened or closed the wave length emitted is constant and also as signals are made with the key correctly connected the Morse formation is perfeet. For medium powers owing to the absence of sparking and potential it is possible to use an ordinary light relay as the signalling key, so that a great increase of speed of transmission results, the receiving station at the same time being able to make full use 01 syntonization available and successfully to employ mechanical recording apparatus. 7

Having described my invention, what I claim is:

1. A wireless telegraph transmitter in which signals and silence periods are effected by shorting and unshorting respectively by means of a key a coil in a tuned circuit coupled to the aerial, characterized in that the signal is made by the closing of the key while maintaining the radiated frequency constant.

2. The method of operating a wireless telegraph transmitter having a coil in a tuned circuit coupled to an aerial and means for shorting and unshorting said coil which consists in making the signal when the key is closed and the silence periods when the key is open while maintaining the radiated frequency constant.

3. The method of operating a wireless telegraph transmitter having a coil in a tuned circuit coupled to an aerial and means for shorting and unshorting said coil which consists in shorting the coil to produce a signal and unshorting the coil to produce a silence period while maintaining the radiated frequency constant.

4. The method of operating a wireless telegraph transmitter having a coil in a tuned circuit coupled to an aerial and means for shorting and unshorting said coil which consists in shorting the coil while maintaining the tuning substal'ltially constant to pro duce asignal and unshorting the coil to produce a silence period.

5. The method of operating a wireless telegraph transmitter having a coil in a tuned circuit coupled to an aerial which consists in uncoupling said coil from the aerial to produce a signal and coupling said coil to the aerialto produce a silence periodwhile maintaining the radiated frequency constant.

6. The method-of,- operatinga wireless;

telegraph transmitter having a coil in 1 a tuned circuit coupled to an aerial and means for shorting and unshortingsaid'coil-which consists in producing a signal by uncoupling saidcoil from the aerial :by shorting 'lt'aIlCl producing a silence period by coupling said.

consists in producing asignal by uncoupling said coil from the aerial while maintaining said tuning substantially constant and period by coupling said producinga silence COIl'lZO the aerial.

8.- In a wireless telegraph transmitter an aerial havin'g'two coils in'v a tuned circuit coupled thereto'in opposition to each other and a means adapted to shortcircnit one of the coils.

9., In, a; wireless telegraph, transmitter; a

tuned {primary circuit, a secondary circuit, a plurality of coils in opposition in the primarycircuitand coupled to the other circuit and means for short circuiting one of said coils.-

10. In a wireless telegraph transmitter, a tuned primary circuit, a secondary circuit, a plurality of coils insaid primary circuit in opposition, coupled to the secondary circui-t and meansrf'or short circuiting one of said coils.

11. In a wireless telegraph transmitter, a tuned primary circuit, a secondary circuit, a pair of coupling coils between said circuits arranged in opposition, said coils having a small co-efiicient ofselfinductionand means for shortcircuiting one ofsaid coils.

NORMAN EUSTA'OE DAVIS. 

